Discovered 1781 by Charles Messier.

M84 has been discovered and cataloged by Charles Messier on March 18, 1781 when he also cataloged 7 more nebulous objects in the same celestial region, all of them member galaxies of the Virgo Cluster, as well as globular cluster M92.

M84 is situated in the heavily populated inner core of the Virgo Cluster of galaxies; it is the very left bright galaxy in our image. The other galaxies in this image are: the bright galaxy slightly below and left of the center is M86, while in the upper left is the edge-on spiral NGC 4388, and below it (in the center of the triangle with the 2 Messiers) is starlike NGC 4387. Below M86 near the lower edge is dim edgewise NGC 4402. Small and at the very top center is the barred spiral NGC 4413, and below it to the right NGC 4425. The pair of galaxies at the very right is the interacting pair of NGC 4438 (above) and NGC 4435. This photogenic group was captured in more images including M84 and M86. Deep images of this group have revealed that these galaxies are actually much larger than indicated in conventional images, as the one in this page. In addition, we have images of the whole central part of the Virgo Cluster: M87 together with Markarian's chain around M84 and M86.

M84 alone can be seen in the DSSM image. From its appearance, it was longly classified as an E1 elliptical, which is also in accordance that it is only populated by old yellowish stars (NED still has this classification). However, there is now some evidence that this may actually be a face-on lenticular galaxy. As seen in this image, M84 has a nice system of globular clusters, which is however much less crowded than the system of its giant neighbor 1/2 degree south and 2 degrees east, M87, which may mark the center of the Virgo cluster.

As a peculiar (but perhaps no way unique) feature, M84 contains a central machine which ejects two small but conspicuous jets, which can be seen in the radio light, as seen in the NRAO image published some time ago. This object was also target of a 1997 investigation of M84 by the Hubble Space Telescope, shortly after its second service mission (STS-82); it was found that the nucleus of M84 contains a massive central object of 300 million solar masses, concentrated in less than 26 light years from the galaxy's center.

A supernova (1957B) was discovered by G. Romano in Italy on May 18,1957 at mag 13. It had also been present on pre-discovery photographic plates taken at Mt. Palomar a month earlier. Supernova 1980I was discovered on June 13, 1980 by Rosker and reached magnitude 14.0. Supernova 1991bg appeared in M84 on Dec 3, 1991 and reached mag 14.